Spark plug for internal-combustion engines



Jlily 1929. R. COLIN SPARK PLUG FOR INTERNAL COMBUSTION ENGINES FiledJune 6, 1927 I l I Patented July 2, 1929.

PATENT OFFICE.

RENE COLIN, OF STRASBOUBG, FRANCE.

' seam: PLUG ron INTERNAL-COMBUSTION madness.

Application filed June 6,

This invention relates to a spark plug for internal combustion engines,which is arranged in such a manner, that the action of the spark plugand the explosion of the cylinder can he observed from the outside.

For this purpose certain parts of the spark plug are made of transparentmaterials.

This characteristic permits observation of the functioning of the'sparkplug as well as the explosion directly from the outside, without itbeing necessary. to unscrew the spark plug. As the observations are madewhile the spark plug is in place, control is naturally much moreeffective. Several forms of the subject-matter of the invention areshown in the drawings.

Fig. 1 is a section through a complete'spark plug.-

Fig. 2 a sect-ion through another form of spark plug. v

Fig. 3 a section through the special form ofv an electrmle for the sparkplug.

The spark plug of the ordinary style consists of a body 1, a centralscrew 2, in which 25 is arranged the central electrode 3. which latteris surrounded by an insulating body 4 of mica or the like, and at bothends, of the screw provided with insulating discs 5 and 6 of mica or thelike. Between the inner ft) abutment of the body 1 and the threadedportion of the screw 2 a tubular piece 7 of transparent insulating ornot insulating material is arranged so that the flame of the explosionin the cylinder, which flame extends up into the inner hollow space ofthe spark plug,

sion of which compensates for the different" 1921. Serial No. 196,956.

expansion coefiicients, in order to guarantee the absolute tightness ofthe spark plugs during use.

One can also use a socket, consisting of transparent material and whichat necessary points is surrounded by a metal sleeve; It is 5 alsopossible to form the electrode itself wholly or partly of transparent orsemitransparent material.

Fig. 3 for instance shows a section through an electrode permitting theobservation of 65 the spark plug from the outside. The electrodeconsists in this case of a tube 10, having at its upper portion a threadfor receiving the necessary access'ories- At the opposite end, however,are provided one or several abutment-s 11 serving for the transmissionsof the spark to the socket portion in the usual manner. The inside ofthis tube 10 is filled by a transparent bodyenabling observation fromthe outside.

Such transparent or semitransparent parts of the spark plug can bemanufactured of the various insulating or noninsulating materialsavailable.

Having thus described my invention what I claim is:

A spark'plug comprising a body having an observation opening in itswall, a transparent insulating member in said body andextending acrosssaid observation opening,

an electrode extending through said transparent insulating member and ascrew sleeve threaded in said body andarranged to secure said insulatingelement in place, the wall of said screw sleeve being of such thicknessas to provide an annular space extending to said insulating element andform a darkened observation zone through which sparks which illuminatesaid insulating member may be observed.

In witnes 's whereof I afiix my signature.

- RENE COLIN.

